The present invention refers to a system and to a process for obtaining vacuum and for supplying fluid in hermetic circuits, particularly applied to refrigeration circuits of refrigeration appliances, such as refrigerators, freezers and air conditioners.
The refrigeration appliances have a refrigeration circuit pressurized with a refrigerant fluid, for example isobutane, which should be introduced in this circuit free from impurities and humidity, in order to avoid, for instance, the oxidation of the components enclosed inside the hermetic housing of the compressor of said refrigeration appliances.
Before supplying the refrigerant fluid, it is necessary to submit the refrigeration circuit to a determined vacuum condition. This vacuum condition is achieved in a producing unit, where each type of refrigeration appliance, for example a freezer or an air conditioner, is processed in a specific vacuum system (carrousel or mono-via), which is connected to vacuum pumps for a determined time, in order to be submitted to a process of depressurization and dehydration, before being conducted to a supply station, where it will receive a proper charge of refrigerant fluid.
In order to receive the refrigerant fluid, each refrigeration appliance is disconnected from the respective vacuum pump and individually connected to a refrigerant fluid supply station in a subsequent step to the vacuum producing process. The vacuum may be obtained only in the low pressure side of the refrigeration circuit of the refrigeration appliance or, simultaneously, in both high and low pressure sides of said circuit, this choice being a function of the time available to the process and of the level of the vacuum to be obtained.
In order to be conducted to the supply station, each refrigeration appliance is disconnected from the vacuum station after the time interval programed for obtaining said vacuum has elapsed. However, the disconnections from the vacuum stations usually cause slight pressure failures in the refrigeration circuit, a vacuum recovery being therefore needed just after the connection in the supply station, requiring the supply stations to be equipped with an additional vacuum pump.
In another known processes, the vacuum production occurs in a vacuum producing unit, where several refrigeration units are connected to a single vacuum pump, of high capacity, or by means of multiple vacuum producing units, each having a pump with a sufficient capacity for a single refrigeration unit.
In all these systems, each unit of refrigeration appliance is disconnected from the respective vacuum pump and subsequently connected to the refrigerant fluid supply station in order to receive the respective charge of said fluid.
The processes for obtaining vacuum and for supplying refrigerant fluid in refrigeration appliances have some deficiencies, such as the vacuum failure during the successive disconnections, contamination of the refrigeration circuit with humidity, due to vacuum failure, thereby requiring a new vacuum producing step, before the refrigeration appliance receives the charge of refrigerant fluid.
Each new vacuum producing step for a refrigeration appliance requires a stop in the production line of the vacuum producing unit, in order to avoid that the hermetic circuits, which have been already processed and provided with a determined vacuum value, remain a long time without the respective charge of refrigerant fluid, which condition may be jeopardized, allowing, with time, humidity to penetrate inside the refrigeration circuit.
Another deficiency of the known techniques refers to the same processing time for all the refrigeration appliances to be processed for obtaining vacuum and refrigerant fluid supply.
Thus, it is an objective of the present invention to provide a system for supplying fluid in hermetic systems which, in a single producing unit, allows to obtain vacuum and the immediate supply of refrigerant fluid for different lines of refrigeration appliances. Another objective of the present invention is to provide a process for supplying fluid in hermetic systems, which avoids the possibility of vacuum failure in the refrigeration appliances in which the vacuum has been already produced, and which also avoids the need of additional steps for obtaining vacuum in the refrigeration appliances, further eliminating the interruptions in the process for obtaining vacuum and refrigerant fluid supply in the production line.
A further objective is to provide a system and a process for supplying refrigerant fluid, which allows to differentiate the time of each operational step in the production line, as a function of the needs of each said step, or of the processing times required for each type of refrigeration appliance.
Another objective of the invention is to provide a process, such as mentioned above, which minimizes the possibility of contaminating the refrigeration circuit which is going to receive the refrigerant fluid.
These and other objectives are achieved by a system for supplying fluid in hermetic circuits, comprising: a plurality of processing cells, which will receive, individually, a hermetic circuit; a plurality of connecting means, which are each mounted to a respective processing cell and coupleable to the hermetic circuit received therein and connected to a vacuum pump and to a fluid supply source, in order to selectively and sequentially submit said hermetic circuit to vacuum and fluid supply conditions; and a control unit, which is operatively connected to each connecting means, in order to control the operation of the connecting means, so as to selectively and sequentially produce in the hermetic circuit the desired vacuum and fluid supply conditions.
The objectives of the present invention are further attained by a process for supplying fluid in hermetic circuits, comprising the following steps: a- positioning a hermetic circuit in a processing cell; b- connecting the hermetic circuit, in a processing cell, to a respective connecting means connected to a vacuum pump and to a fluid supply source; c- providing a selective and sequential fluid communication of the connecting means with the vacuum pump and with a respective fluid supply source, in order to instruct the production of vacuum in said hermetic circuit; and d- instructing, in the processing cell where is found the hermetic circuit, the supply of a fluid charge to said hermetic circuit, after a determined vacuum condition has been obtained in the latter.